Solubility Of CO₂ In Simulated Deep Saline Aquifers Solution Under Geological Storage Conditions

With the continuous development of human society,the consumption and demand of energy resources such as fossil fuels and coal are also increasing,which leads to excessive emissions of greenhouse gases,such as carbon dioxide.However,CO₂ can survive in the atmospheric environment for a long time,and its warming effect greatly affects the global climate change,which in turn has a serious negative impact on the global environment.And as one of the most effective CO₂ emission reduction technologies,the CO₂ capture and storage technology（CCS）can greatly reduce CO₂ emissions in industrial production processes around the world,and reduce the greenhouse effect caused by excessive CO₂,and it has become the focus of attention.Among them,the geological storage technology of CO₂ has the most development potential and prospects,and has become the research hotspot of various scientific research institutions.In this study,the solubility measurement method of CO₂-salt solution system was established by our research group.The high temperature and high pressure micro visible fused silica capillary cell（FSCC）was used to replace the traditional high pressure stainless steel equilibrium kettle,combined with circulating pump,80MPa phase equilibrium kettle,a heating and cooling stage,30 MPa quantitative pump and Raman spectroscopy with microvideo recording system.And in this paper,the change of CO₂ Solubility with buried depth in Deep saline aquifers solution simulated by different salinity（8.25g/L,33.0g/L,66.0g/L,99.0g/L）under different temperature and pressure conditions of different buried depth（800m,1300m,1800m,2300m,2800m）is studied.It provides a powerful experimental basis for the development of CO₂geological storage technology.In this experiment,the linear relationship between CO₂-H₂O Raman peak intensity ratio and CO₂ concentration in the solution was used to draw the corresponding standard curve by means of the Raman spectra of the aqueous phase in simulated salt solution system.And the corresponding linear fitting is carried out and the relationship between the two is obtained,which is used to calculate the solubility data of CO₂ in simulated salt solutions with different salinity under different temperature and pressure conditions.The experimental results show that:（1）With the increase of burial depth,the solubility of CO₂ in simulated salt solution decreases first and then increases,and the turning point of change occurs at the depth of about 1800m.（2）Under the same temperature and pressure conditions,with the increase of salinity of the simulated salt solution,the solubility of CO₂ in the salt solution decreases continuously,and the change trend of CO₂ solubility gradually slows down.（3）By fitting the change curve of CO₂ solubility at different buried depths,it is found that there is a cubic polynomial non-linear relationship between CO₂ solubility and burial depths.（4）Based on the relationship between the depth of the deep saline aquifers and the solubility of CO₂,the existing formula for estimating the dissolved storage capacity of the deep saline aquifers is modified,and the total amount of CO₂ dissolved in deep saline aquifers with different storage area and different thickness of sedimentary aquifers is calculated.（5）According to the experimental data of this subject,the formula for calculating the CO₂ solubility of simulated deep saline aquifers solution under different salinity and buried depth is obtained.